For analyzing a change in chemical state of a polymer material containing at least one diene rubber caused by deterioration, for example, an infrared spectroscopy (FT-IR), nuclear magnetic resonance analysis (NMR), and X-ray photoelectron spectroscopy (XPS) and the like are commonly employed. Though FT-IR or NMR allows a detailed analysis of the chemical state, the obtained information is bulk information and therefore it is difficult to analyze in detail the chemical state after deterioration which starts at a sample surface.
On the other hand, XPS is a surface-sensitive method and is therefore thought to be effective for analysis of a change in chemical state caused by deterioration. As one example of analysis and evaluation of deterioration by XPS, FIG. 1 shows the results of XPS measurement of the is orbital of carbon in fresh butadiene rubber (BR) , ozone-deteriorated BR, and oxygen-deteriorated BR (carbon K-shell absorption edge of BR).
As shown in FIG. 1, in the XPS measurement, the peak of C═C bond (double bond) and the peak of C—C bond (single bond) overlap each other at around 285 eV, and therefore the chemical states of the different groups cannot be distinguished. Hence, it is difficult to determine the amount of C═C bonds (double bonds) that is reduced by deterioration. Moreover, in FIG. 2 showing the results of XPS measurement of the oxygen K shell absorption edge of BR, no difference is found in the spectra between the ozone-deteriorated BR and oxygen-deteriorated BR. Hence, a detailed analysis of deterioration by XPS is difficult.
Meanwhile, measurement of X-ray absorption spectra of polymers has also been carried out as disclosed in Non Patent Literatures 1 to 3. However, no disclosure is found in any literatures including these non patent literatures that deterioration factors can be distinguished based on the X-ray absorption spectra.